1. Field of the Invention
The present invention relates generally to medical apparatus and methods and more particularly to devices and methods for mixing components prior to delivery of the mixed components to an anatomical site.
It is frequently desirable or necessary to mix components of a medical preparation together immediately prior to use. It is also desirable to mix components in single use batches, to assure consistency in the delivery of the combined components. Compositions such as bone fillers, bone cements, medical adhesives, dental adhesives, and the like, often rely on mixing syringes combining components and subsequently delivering the combined components to the desired anatomical location. Frequently, the mixing syringes or other apparatus are also used for storing and maintaining sterility of the components for extended periods prior to the time when they are to be used.
To be successful, such storage and mixing apparatus should meet a number of objectives. First, the apparatus must store the separate components in a manner that provides complete isolation prior to mixing. Once it is desired to mix the components, however, mixing must be rapid, thorough, and require minimum effort by the user. Many prior art devices rely on shaking or vibrating the mixing syringe or other container to achieve adequate mixing of the components. Shaking or vibration, however, seldom achieves complete mixing and can compromise the design of the syringe. Moreover, such devices frequently require external mixing systems which can be expensive and inconvenient to use.
For these reasons, it would be desirable to provide improved mixing syringes and other apparatus for combining and mixing components of medical and dental compositions prior to use in single use batches. It would be further desirable if such mixing syringes and apparatus were also useful for directly or indirectly delivering the combined and mixed materials to the anatomical site of interest. Such mixing syringes and apparatus should be relatively inexpensive to produce, should provide complete and reliable isolation of the components to be mixed prior to use, should be suitable for both liquid-powder and liquid-liquid mixes, should be relatively simple to use, and should provide precise and accurate delivery of the mixed compositions. At least some of these objectives will be met by the inventions described herein below.
2. Description of Background Art
U.S. Pat. No. 3,739,947 and U.S. Pat. No. 3,684,136 describe a syringe (comparable to an injection syringe without needle) that contains a sealed liquid reservoir for first component on one end. The space to accommodate the second component is hermetically separated from this liquid reservoir. To produce the mixture, the seal is perforated so that separation of the two components is eliminated (the syringe is activated).
GB 2239818 describes mixing apparatus that contains no integrated mechanical mixing device. After combining of the two components, this apparatus must be shaken for mixing. There is a hazard that a homogeneous mixture will not be produced, especially since it is difficult to mix viscous material systems by shaking. The two containers to accommodate the two components are sealed relative to each other by means of a membrane which is difficult and costly to fabricate.
U.S. Pat. No. 4,551,135 describes a mixing device for extrusion of two different components where the device includes two vessels which must be separated for storage of the two components before extrusion.
U.S. Pat. No. 3,756,571 describes an apparatus that requires an expensive, external shaking or mixing device for homogeneous mixing of two components. The container to accommodate the liquid component is not suitable for extrusion of the finished mixture. A seal (film) provides separation of the two components (powder and liquid) in the two vessels.
U.S. Pat. No. 3,828,434 describes a mixing capsule in which homogeneous mixing of two components is provided by an external shaking device.
EP 0 245 788 A1 describes an apparatus including two containers to accommodate the two components. The containers are hermetically sealed from each other, and the apparatus requires an external mixing device.
EP 0 397 589 A1 describes an apparatus where a first component (liquid) is conveyed by means of a pressure difference between a first container holding the liquid to a second container holding a second component (powder). The container for the liquid is sealed relative to the other containers.
U.S. Pat. No. 3,831,742, U.S. Pat. No. 3,917,062 and U.S. Pat. No. 4,084,320 describe an apparatus which requires an external mixing device.
EP 0 380 867 A1 describes an apparatus intended for mixing of bone cements using partial vacuum. One container must be coupled to another container. The two containers are therefore not integrated in a common enclosure.
U.S. Pat. No. 5,058,770 describes an apparatus with two containers that contain the two components to be mixed. The containers must be screwed together first before the mixing process. The vessel containing the liquid is closed by a membrane that must be perforated for mixing of the two components.